Photonic systems typically require optical connections to be made between a photonic integrated circuit (PIC) and another optical device, such as an optical-electrical (OE) printed circuit board. For example, optical signals traveling in optical waveguides of the OE printed circuit board typically need to be in optical communication with a photonic device in the form of a detector (e.g., light sensor) on the PIC.
In some cases, the optical connection can be formed using optical fibers. However, low-profile packaging requirements dictate the maximum allowable height (clearance) to which the optical fibers can reach. The optical fibers may also need to have nearly right-angle bends to accommodate vertical emitting or vertical detecting photonic devices.
The combination of low-profile packaging requirements and the need for strong bending present challenges to the use of optical fibers for optical interconnections within photonic systems. In particular, the long-term reliability of the optical fibers can be compromised by tensile and compressive stresses and strains imparted to the fiber. Further, the bending loss for strong bends put limits on the fiber diameter that can be used. In addition, precise alignment of the optical fibers to PIC devices such as light sources, detectors and optical waveguides presents additional challenges when fabricating photonic systems. For example, mismatches in the coefficients of thermal expansions of materials used in forming optical-fiber-based interconnectors can lead to misalignment and induced stresses when interfacing with silicon-based PICs.